Mulch Calculator
Wondering how much mulch you need for your garden beds? Our free mulch calculator turns your bed's length, width, and desired depth into cubic yards of mulch and the number of bags to buy — including a 5% waste allowance — plus a bulk-vs-bagged cost comparison so you can see which way to buy is cheaper.
Enter your numbers
Your results
| Cubic feet | — |
| Volume with 5% waste | — |
| Bulk cost | — |
| Bagged cost | — |
Estimates: bag counts include a 5% waste allowance and are rounded up to whole bags. Actual coverage varies with mulch type and how tightly the bags are packed.
How to use this calculator
Measure your garden bed's length and width in feet and enter them above. Pick a mulch depth — 2″, 3″, or 4″, or choose Custom for any other depth in inches — then select your bag size (2 cu ft is the most common). Your results update instantly.
For irregular or L-shaped beds, break the area into rectangles, run each section separately, and add the cubic-yard totals together. Entering your local bulk price per cubic yard and price per bag adds a cost comparison that flags the cheaper option.
How it works
The bed volume is cubic feet = length (ft) × width (ft) × depth (in) ÷ 12, converting inches to feet. That volume divided by 27 gives cubic yards, the unit bulk mulch is sold in. Bag counts build in a 5% waste allowance and round up: bags = ceil(cubic feet × 1.05 ÷ bag size), so you don't run short mid-bed.
When prices are entered, the calculator compares bulk cost = cubic yards × bulk price against bag cost = bags needed × bag price and flags the lower total. The comparison uses your numbers alone — it doesn't include delivery fees or minimums, so check those before you buy.
Frequently asked questions
How deep should mulch be?
2 to 4 inches is the general guideline. Use 2–3 inches for most flower and shrub beds, and 3–4 inches when you want stronger weed suppression. Keep mulch a few inches away from stems and tree trunks — piling it against the plant (a “mulch volcano”) traps moisture and can cause rot.
How many bags of mulch are in a cubic yard?
One cubic yard contains 27 cubic feet. A 2-cu-ft bag is 1/13.5 of a yard, so about 13.5 bags per cubic yard. A 3-cu-ft bag is 1/9 of a yard, or 9 bags per cubic yard. Always round up to whole bags and add a little extra for waste.
Is it cheaper to buy mulch in bulk or bags?
It depends on the job size and local prices. Bulk mulch is usually cheaper per cubic yard, but yards often have minimums and delivery fees, while bags cost more per yard but have no minimum. Enter your local bulk and bag prices above and this calculator flags the cheaper option for your project.
When is the best time to mulch?
Spring is the best time to mulch, once the soil has warmed — it locks in moisture and suppresses weeds for the growing season. A lighter top-up in fall helps insulate roots and enriches the soil as organic mulch breaks down over winter.
What types of mulch are there?
Common types include shredded hardwood or bark, wood chips, pine straw (pine needles), straw, and compost, plus inorganic options like gravel or crushed stone. Organic mulches feed the soil as they decompose but need topping up; stone mulches last longer but add no nutrients and can heat up in full sun.